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Ascend Sierra 2 Speaker Review

amirm

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#1
This is a review and detailed measurements of the Ascend Acoustics Sierra 2 "Reference" Stand-mount Speaker with "RAAL tweeter. It is on kind loan from a member. I *think* they cost $738 each or $1448 for a pair.

The model I have is made out of bamboo but finished in black:

Ascend Acoustics Sierra 2 Bookshelf Stand-mount Speaker Audio Review.jpg

The back panel shows a large, flared port and nice quality binding posts:

Ascend Acoustics Sierra 2 Bookshelf Stand-mount Speaker Back Panel Audio Review.jpg

I was impressed with how stiff the cabinet was as even under heavy load of pounding bass, it would hardly transmit much to the outside. It is still a small speaker but even using one unit, it could fill my large space with sound. You won't confuse it with a 6 foot tower speaker but didn't sound like a little clock radio either. :)

Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections. It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room. All measurements are reference to tweeter axis with the grill removed.

Around 800 points around the speaker were measured (from 20 to 20 kHz) which resulted in well under 1% error in identification of the sound field across full frequency response of 20 to 20 kHz. Final database of measurements and data is 1.2 Gigabytes in size.

Spinorama Audio Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker can be used. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:

Ascend Acoustics Sierra 2 Bookshelf Stand-mount Speaker CEA2034 spinorama Audio Measurements.png


We don't have a dead flat response but with variation being mostly peaks, a bit of EQ in those areas should tame them.

One oddity is that the company measurements show a rising response climbing to 20 kHz. Don't know what explains the discrepancy. Regardless, I rather have it my way than theirs when it comes to sound. :)

Directivity index is not perfect either but is close enough that should allow for some judicious EQ per my note above:

Ascend Acoustics Sierra 2 Bookshelf Stand-mount Speaker CEA2034 spinorama Directivity Index Au...png


Finally, this is a prediction of what sound you may get in a typical room:

Ascend Acoustics Sierra 2 Bookshelf Stand-mount Speaker CEA2034 spinorama Predicted In-room Re...png


It is as to be expected based on measurements we saw before it.

Basic Speaker Measurements
The company specifies minimum impedance of 6 ohms but my sample dipped well below that:

Ascend Acoustics Sierra 2 Bookshelf Stand-mount Speaker Phase and Impedance Audio Measurements.png


Given the bass efficiency of 85 dB and lower, you better have lots of power for amplification.

Distortion measurements showed a concerning peak:

Ascend Acoustics Sierra 2 Bookshelf Stand-mount Speaker distortion Audio Measurements.png


The ribbon tweeter likely hitting some kind of mode and running away on its own. We have a peak in frequency response after it that may be caused by this.

Advanced Speaker Measurements
Ascend Acoustics Sierra 2 Bookshelf Stand-mount Speaker CEA2034 spinorama Early Reflections Au...png


Ascend Acoustics Sierra 2 Bookshelf Stand-mount Speaker CEA2034 spinorama Horizontal Reflectio...png

Ascend Acoustics Sierra 2 Bookshelf Stand-mount Speaker CEA2034 spinorama Vertical Reflections...png


In the following two graphs, look for least amount of "beard" below the main axis response:

Ascend Acoustics Sierra 2 Bookshelf Stand-mount Speaker CEA2034 spinorama Full Horizontal Refl...png


Ascend Acoustics Sierra 2 Bookshelf Stand-mount Speaker CEA2034 spinorama Full Vertical Reflec...png


Eye-candy Speaker Measurements
Contour graph shows that good response remains for a wide window of +- 80 degrees:
Ascend Acoustics Sierra 2 Bookshelf Stand-mount Speaker Contour Horizontal Audio Measurements.png


That means you can have a wide sweet spot, or ability to point the speaker forward and listen to them off-axis.

Vertically is the opposite though:

Ascend Acoustics Sierra 2 Bookshelf Stand-mount Speaker Contour Vertical Audio Measurements.png


Best to put them at ear height (relative to center of the tweeter as I measured).

Ascend Acoustics Sierra 2 Bookshelf Stand-mount Speaker Waterfall Audio Measurements.png

Casual Listening Tests
I don't have a controlled setting for hi-fi speaker testing yet. I just place a single speaker close to my Revel Salon 2 and use its amplifier to listen to single channel. There, the Sierra 2 produced better than expected sound. Its nice and solid enclosure allowed me to turn it up quite high and most of my reference tracks sounded "good." I could move around the speaker left and right with almost no tonality difference (i did this prior to confirming with contour plots above). Vertically though, the angle is quite limited so per earlier note, use stands that allow you to have them at your ear height.

Conclusions
The Ascend Sierra 2 is not perfect but overall, it seems to be a good package. You are getting much better build quality and SPL capability in a small package. And frequency response variations should be correctable to some extent with EQ.

I personally want more perfection in the speaker so would not be buying it myself but you have the data to decide for yourself.

------------
As always, questions, comments, recommendations, etc. are welcome.

I have been so busy with equipment testing that I have not started my vegetable seedlings. Fortunately, I read on the Internet that they sell a special liquid you put on the seeds that makes them sprout 10 times faster! I love to get some but they want $100 for a little bottle. So please donate some money so I can afford to get them and catch up on my gardening using : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 

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amirm

amirm

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Thread Starter #2
@MZKM is out but was kind enough to compute the preference scores for me:
Preference Rating
SCORE: 4.1
SCORE w/ subwoofer: 6.3
 

aarons915

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#3
Very EQ'able speaker but not as neutral as I was expecting. I've heard some say that these are a bit thin sounding as well, which the measurements definitely back up but with a bit of EQ in the mids/highs I bet that would go away and they'd be much better.

Hopefully someone will send in the new Sierra 2 EX soon to compare, I've read they are voiced "warmer" than these and they should be more neutral considering the better midwoofer.
 

maty

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#5


Resized

Ascend Acoustics Sierra 2 Bookshelf bode resized.png


Something is wrong. It seems other loudspeaker, maybe from a measurement of an older version, with another tweeter and crossover, I say.
 
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MZKM

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#6
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amirm

amirm

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Thread Starter #9
Something is wrong. It seems other loudspeaker, maybe from a measurement of an older version, with another tweeter and crossover, I say.
Has there been other revisions of this model?
 

MZKM

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#12
Has there been other revisions of this model?
They show it being released in 2014, and no news updates for the speaker and no mentions on the product page.

They state:
Left / right pairs are matched by hand to within ± 1dB and we are including a printout of the actual production line response measurements of each speaker.
Maybe ask the owner if he still has it.
 

VeerK

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#15
I've been waiting for this review for a while, as a former owner of the Sierra 2's, they were incredibly well-reviewed, and I personally loved them as well. I too would like to see the Sierra 2 EX reviewed, the Sierra 2 measurements Amir took show there is some room for improvement.

That being said, does someone have the Salk Silk Monitors they could loan to Amir? Silks used to be the holy grail of 2-ways, would love to see how they measure in the Klippel.

Either way, will always love the Sierra 2s!
 
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#17
Tweeter resonance at 3400 Hz ????
Ribbon tweeters generally need to be crossed higher than domes. Wondering if this version of the RAAL should be crossed no lower than 3.5 Khz.

I own the towers with the dedicated midrange and larger RAAL i could be convinced to send the Horizon/RAAL for testing if there is considerable interest.
 

AnalogSteph

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#18
Tweeter resonance at 3400 Hz ????
Just the effect of typical Leaky Ribbon Disease + crossover, I'd say... I've seen one or two Sealed Ribbon Tweeters lately, that approach should fix the issues with excessive excursion. (Waveguide still required though. The latest ADAMs seem to be quite good in that regard.)
 

VeerK

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#19
Ribbon tweeters generally need to be crossed higher than domes. Wondering if this version of the RAAL should be crossed no lower than 3.5 Khz.

I own the towers with the dedicated midrange and larger RAAL i could be convinced to send the Horizon/RAAL for testing if there is considerable interest.
The Sierra 2 uses the RAAL 64-10, which is less flexible than some of the larger RAAL designs. I know RAAL likes to advertise the 70-20XR can be crossed as low as 1.8K, which isn't advisable, but shouldn't show the weird resonance that the 64-10 is exhibiting.
 

aarons915

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#20
For anyone interested, I plugged in the listening window to REW to make some basic EQ to flatten it out. I left the tweeter range alone since most people seem to like the highs of the ribbon. This should make the speaker sound more balanced in the mids. This is a good speaker to EQ since the directivity index is very smooth.

Sierra2EQ.png
 
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